The whole point is that there will be more power to constituency parties and to members. Yes, there will be some resistance - some MPs may move to other parties or stand as independents - but in the long run, the party, by the time of the next election, the party will be on stronger footing.
I've said earlier on in this thread, I can't see Labour winning the next election, but if Corbyn wins and he enacts the changes he wants, in the long run, the party will be based on a formidable mass membership
Oh well, let us wait and see what happens!